Don't create an extra fd bitmap to allocate a new fd.

3 files changed, 80 insertions, 0 deletions

diff --git a/test/perf/BUILD b/test/perf/BUILD
index 75b5003e2..08e04d8ad 100644
--- a/test/perf/BUILD
+++ b/test/perf/BUILD
@@ -70,6 +70,13 @@ syscall_test(
 )
 
 syscall_test(
+    size = "large",
+    add_overlay = True,
+    debug = False,
+    test = "//test/perf/linux:dup_benchmark",
+)
+
+syscall_test(
     debug = False,
     test = "//test/perf/linux:pipe_benchmark",
 )
diff --git a/test/perf/linux/BUILD b/test/perf/linux/BUILD
index dd1d2438c..4511611ad 100644
--- a/test/perf/linux/BUILD
+++ b/test/perf/linux/BUILD
@@ -109,6 +109,22 @@ cc_binary(
 )
 
 cc_binary(
+    name = "dup_benchmark",
+    testonly = 1,
+    srcs = [
+        "dup_benchmark.cc",
+    ],
+    deps = [
+        gbenchmark,
+        gtest,
+        "//test/util:fs_util",
+        "//test/util:logging",
+        "//test/util:temp_path",
+        "//test/util:test_main",
+    ],
+)
+
+cc_binary(
     name = "read_benchmark",
     testonly = 1,
     srcs = [
diff --git a/test/perf/linux/dup_benchmark.cc b/test/perf/linux/dup_benchmark.cc
new file mode 100644
index 000000000..fcf14368b
--- /dev/null
+++ b/test/perf/linux/dup_benchmark.cc
@@ -0,0 +1,57 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "benchmark/benchmark.h"
+#include "test/util/fs_util.h"
+#include "test/util/logging.h"
+#include "test/util/temp_path.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+void BM_Dup(benchmark::State& state) {
+  const int size = state.range(0);
+
+  for (auto _ : state) {
+    std::vector<int> v;
+    for (int i = 0; i < size; i++) {
+      int fd = dup(2);
+      TEST_CHECK(fd != -1);
+      v.push_back(fd);
+    }
+    for (int i = 0; i < size; i++) {
+      int fd = v[i];
+      close(fd);
+    }
+  }
+  state.SetItemsProcessed(state.iterations() * size);
+}
+
+BENCHMARK(BM_Dup)->Range(1, 1 << 15)->UseRealTime();
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor